There are various industrial applications in which an elongated shaft, also referred to as a pin, must be driven translationally, i.e., in the direction of the elongated (longitudinal) axis of the pin. Typically, the pin has a pin head at one end for engagement by the drive actuator assembly. In various applications, it may be desirable or necessary to mechanically or thermally isolate, in at least some respect, the pin from the actuator assembly.
For example, in hot runner systems used in injection molding, valve pins are used to open and close the gate to a cavity in the mold in which the molded part is formed. Each valve pin is driven by an actuator assembly and extends through various parts of the injection molding machine which are at different temperatures (e.g. heated nozzle, heated manifold, cold mold and mounting plates). These temperature differences and/or differences in thermal expansion (during heating/cooling) of the various parts can place undesirable side load forces on the pin, causing the pin to become misaligned, bent or even broken. Still further, the pin may transmit heat from a hot part to a cold part of the machine, which again would be undesirable. There is thus a need to provide a mechanism for coupling a pin to an actuator which translationally drives the pin so as to maintain alignment, prevent deformation of the pin and/or prevent undesired thermal transmission to the actuator and/or other parts of the injection molding apparatus.